Method and apparatus for data reproduction

ABSTRACT

A data reproduction method and apparatus includes first circuitry to produce an information signal from a storage medium. The information signal includes copy control information. Detection circuitry is provided to detect the copy control information. Control circuitry is provided to operate the first circuitry to selectively output the information signal based on the detection result of the detection circuitry.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is related to and claims priority from JapanesePatent Application No. 11-323652, filed on Nov. 15, 1999 and JapanesePatent Application No. 00-073777, filed on Mar. 16, 2000.

BACKGROUND OF THE INVENTION

The present invention relates to a method of transmitting another databy embedding it in image and/or voice data and to an apparatus forreproducing the transmitted data. Specifically, it relates to a datareproduction apparatus comprising LSI circuitry having the function ofdetecting embedded data.

Technologies for embedding another data in image, voice and text dataare also called “data hiding”, “watermark”, and “electronic watermark”and have been investigated as a technology for embedding identificationinformation or notes connected with these image, voice and text data.

These technologies have been recently been applied as a technology forembedding data for the protection of the copyright of these informationto prevent illegal operation such as illegal reproduction. Thetechnologies are described in “Nikkei Electronics” published by NikkeiBP Co. (pp. 149 to 162, Feb. 24, 1997).

If data to be embedded are deteriorated by processing operation such asthe filtering and/or compression of original data, it loses the functionof preventing illegal operation. Therefore, the method of embedding datais changed or data is embedded repeatedly so that the data still remaineffective after these processes are carried out.

Various permissions concerning the limitation of reproduction areconceivable for original data. For example, original data can bereproduced, cannot be reproduced or can be reproduced only once inconnection with copyright. It is now being considered that such controlof reproduction is to be carried out by embedding data corresponding tothese permissions and detecting it.

Heretofore, in the research and development of the function of detectingembedded data (to be referred to as “watermark detection function”hereinafter), special hardware and digital signal processors (DSP) havebeen used as watermark detection devices. The reason for this is thatthe data processing required for the implementation of a watermarkdetection device is complicated and high operation speed is required. Asa result, the cost of a watermark detection device is significantlylarge compared with the cost of a system incorporating this device.

Owing to recent progress made in semiconductor technology, theperformance-cost ratio of a high-speed arithmetic unit greatly improves.Considering that devices which carry out reproduction control areimage/voice reproduction devices for domestic use such as DVD videoplayers and that they are relatively inexpensive, there still remainssuch a problem that costs required for the addition of a watermarkdetection function cannot be negligible.

To solve the above problem, a watermark detection circuit must be madeinexpensive by reducing its scale. Generally speaking, to cut the costof a digital arithmetic unit while maintaining its certain functions,the following methods are effective:

(1) a portion where parallel processing is carried out is changed toperform a single processing in order to carry out serial processing, and

(2) arithmetic processing blocks such as a memory, adder and multiplierare made general-purpose blocks to be shared in each stage of arithmeticprocessing.

The downside of the above method is that the time required forprocessing is prolonged though they are effective in cost reduction.

The problem that the processing time required for watermark detection isprolonged will be described hereinafter, taking the case where DVD videoreproduction which will be controlled shortly is carried out by a DVDplayer and a DVD-ROM drive.

Since DVD video data recorded on a DVD disk are MPEG2 formatted, thedecoding of MPEG2 formatted data must be carried out to correctlyreproduce original information. MPEG2 specifies the lowest datareproduction rate required for image and voice data at the time ofdecoding. When the transfer rate of data input into an MPEG2 decoder islower than this rate, image and voice data cannot be reproducedcorrectly. Therefore, the MPEG2 data transfer rate has a lower limit.

Meanwhile, the data transfer rate which enables watermark detection islimited for the above reason. Therefore, the data transfer rate whichenables watermark detection cannot be lower than the lower limit of theabove MPEG2 data transfer rate.

In the DVD-ROM drive, how fast data can be transferred compared with theordinary data transfer rate as an additional value of a product isconsidered to be the most important point. When the ordinary transferrate specified by the standards is 1, DVD-ROM drives which can transferdata at a maximum data transfer rate 6 to 10 times higher than theordinary transfer rate are already available on the market. Thereduction of the data transfer rates of these products for watermarkdetection is not allowed from the viewpoint of product value.

Therefore, watermark detection from the output data of a DVD-ROM drivehaving a high data transfer rate involves more difficulties than in aDVD player in terms of data transfer rate which enables watermarkdetection.

As described above, to introduce reproduction control means making useof watermarks, such problems as costs required for the addition of awatermark detection function and processing speed which enableswatermark detection must be solved at the same time. This is a big themeto be targeted.

SUMMARY OF THE INVENTION

The present invention relates to a method and apparatus for playback offirst data contained, for example on a storage medium, where the firstdata is some combination of audio and video information and includessecond data. According to the invention, the first data is produced by afirst circuit. At least some of the first data is delivered to a datastore, including the second data. The data contained in the data storeis processed, and a detection result is produced based at least on thesecond data. The first circuit is controlled by a second circuit toselectively output the first data based on the detection result.

In an embodiment of the invention, a detection circuit separate from thefirst circuit is provided to produce the detection result. In variationsof the embodiment, the detection circuitry can provide verificationfunctions such as repeated detection of multiple occurrences of thesecond data before asserting a detection signal. The detection circuitrycan interact with the second circuitry to verify the integrity of thecircuitry and thus prevent unauthorized tampering with the circuitry.The detection circuitry can used encryption techniques to thwartattempts to alter the signal.

The invention provides the advantage wherein the first data can beprocessed by the first circuit at a high data transfer rate. Thus, forexample, in an MPEG-2 application, the data rate can be sufficientlyhigh to provide faithful reproduction of the signal. At the same time,the detection circuit can provide the watermark detection functionwithout restricting the conversion speed of the first circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the present invention can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings:

FIG. 1 is a diagram showing an example of a reproduction apparatushaving a watermark detection function according to the presentinvention;

FIG. 2 is a flowchart showing an example of a buffer memory controlmethod for watermark detection according to the present invention;

FIG. 3 is a diagram showing an example of data flow related to thewatermark detection operation of a data reproduction apparatus having awatermark detection function according to the present invention;

FIG. 4 is a diagram showing an example of data flow related to thewatermark detection operation of a data reproduction apparatus having awatermark detection function according to the present invention;

FIG. 5 is a diagram showing an example of data flow related to thewatermark detection operation of a data reproduction apparatus having awatermark detection function according to the present invention; and

FIG. 6 is a diagram showing an example of data flow related to thewatermark detection operation of a data reproduction apparatus having awatermark detection function according to the present invention.

DESCRIPTION OF THE EMBODIMENTS

An optical disk reproduction system will be described as an example. Itshould be understood that the present invention is not limited to theoptical disk reproduction system but can be applied to general datarecording and reproduction apparatuses including an optical diskrecording and reproduction apparatus and a magnetic recording andreproduction apparatus.

A case where the type of embedded data is reproduction controlinformation for the protection of copyright is taken into consideration.As a matter of course, the embedded information is not limited toreproduction control information and may be information indicative ofthe type of data or control information corresponding to each recordingmedium.

When data are to be reproduced, reproduction control for the protectionof copyright may be necessary. Data may be transmitted by waves likebroadcasting data and recorded on a disk or cassette as a medium.Therefore, reproduction control information is detected according to theform of data and reproduction control or recording control must becarried out accordingly.

FIG. 1 shows an example of the constitution of a data reproductionapparatus having a watermark detection function according to the presentinvention.

In FIG. 1, reference numeral 11 denotes an optical disk which is arecording medium, 12 pick-up, 13 preamplifier, 14 reproduction signalprocessing block, 15 reproduction signal output processing block, 16data buffer control block, 17 watermark detection processing block, 18signal output terminal, 19 system control processing block, 20 diskcontrol processing block, 21 servo control processing block, 22 diskmotor, 23 buffer memory, 24 reproduction data, 25 exclusive data busbetween the watermark detection processing block 17 and the systemcontrol processing block 19, and 26 general-purpose data bus in theoptical disk reproduction system.

The reproduction signal processing block 14 serves as reproductionprocessing means of processing the reproduction of first data which isimage and voice information and second data which is additionalinformation to the first data embedded in the first data from aninformation recording medium. The watermark detection processing block17 serves as detection means of detecting the second data embedded inthe first data. The data buffer control block 16 and the system controlprocessing block 19 serve as data selection means of selecting datarequired for the detection of the second data embedded in the first datafrom the first data. The buffer memory 23 serves as data storage meansof storing first data required for the detection of the second data. Thereproduction-signal output processing block 15 and the system controlprocessing block 19 serve as reproduction control means of controllingreproduction by the reproduction processing means according to thedetection result of the detection means.

A signal reproduced by the pick-up 12 from the optical disk 11 isamplified by the preamplifier 13 and input into the reproduction signalprocessing block 14.

The reproduction signal processing block 14 serves as reproductionprocessing means of processing the reproduction of first data which isimage and voice information and second data which is additional data tothe first data embedded in the first data from an information recordingmedium and carries out the processing of outputting a digital signalsuch as the rearrangement of data or the correction of an erroraccording to a format based on which a reproduction signal is recorded.Since this block is not directly related to the present invention, itsdetailed description is omitted.

The reproduction signal output processing block 15 rearranges outputdata according to a predetermined interface format such as ATAPI orSCSI, controls a buffer or responds to a command. Since this block isnot directly related to the present invention, its detailed descriptionis omitted.

The data buffer control block 16 temporarily stores processed data 24which may include watermark information in the buffer memory 23.

The watermark detection processing block 17 serves as detection means ofdetecting the second data embedded in the first data, reads datatemporarily stored in the buffer memory 23 through the data buffercontrol block 16 and processes a digital signal to detect watermarkinformation from the data. The disk control processing block 20 controlsthe rotation of an optical disk.

The servo control processing block 21 carries out the servo control of apick-up actuator (included in the pick-up 12 and not shown) and apick-up position control motor (not shown).

The system control processing block 19 controls the entire optical diskreproduction system and serves as information recording medium judgingmeans for detecting the type of the information recording medium andreproduction control means of controlling reproduction by thereproduction processing means according to the detection result of thedetection means, and controls the operation of the apparatus whilecommunicating information required for control with the processingblocks. The type of the information recording medium is judged by thissystem control processing block 19.

As for reproduction control, watermark information output from thewatermark detection processing block 17 is referred to, and the outputof the output processing block 15 is allowed to be output to the outsideof the apparatus through the signal output terminal 18 if there is noproblem with reproduction control and not allowed to be output to theoutside of the apparatus through the signal output terminal 18 if thereis a problem with reproduction control. When this judgment is to bemade, the result of judgment on the type of the information recordingmedium may be referred to.

The watermark detection processing block 17 processes the recognition ofthe existence of watermarks from the output data of the data buffercontrol block 16 and the restoration of data embedded in watermarks whenthe watermarks are embedded. The operation of the watermark detectionprocessing block 17 changes according to a format when each watermark isembedded. Since this watermark embedding format is hidden and notdirectly related to the present invention, its description is omitted.

The recognition result of the existence of watermarks obtained by thewatermark detection processing block 17 and the data restored from theembedded watermarks are given to the system control processing block 19.

The system control processing block 19 receives information on theexistence of watermarks and the data restored from the watermarks whenthe watermarks are existent and controls the optical disk reproductionsystem using these. The system control processing block may judgewhether the first data is allowed to be output from the signal outputterminal having a specific format on the basis of both of data informedfrom the detection means and data on the type of the informationrecording medium which records the first data and controls such that thefirst data is output from the specific signal output terminal when thefirst data is allowed.

The watermark detection processing block 17 recognizes the existence ofwatermarks and restores the data of the embedded watermarks. In theprocessing of detecting the watermarks, the watermarks may not bedetected due to the insufficient embedding strength of the watermarks,the deterioration of a recording medium or the deterioration ofwatermark signals by image processing or reproduction processing such asthe enlargement or reduction of image data embedded with the watermarksthough the watermarks are embedded.

On the contrary, there may occur a case where the existence ofwatermarks is erroneously detected even when the watermarks are notembedded. Since it is likely that an erroneous result may be obtained ifthe result of one time of detection is directly used for reproductioncontrol, when the same detection result is obtained a firstpredetermined number of times continuously, the result is judged aseffective and transmitted to the system control processing block 19 andused for reproduction control.

Even when watermark detection and judgment are carried out by the abovemethod, the possibility of erroneous judgment cannot be completelyeliminated. Then, means of correcting erroneous judgment even when it ismade is necessary. Then, after a watermark is detected the firstpredetermined number of times continuously and this result is judged astrue and transmitted to the system control processing block 19 asdescribed above, only when a detection result different from the firstdetection result is obtained a second predetermined number of timescontinuously, the judgment result is updated. The second predeterminednumber of times may be equal to or larger than the first predeterminednumber of times.

For instance, when a digital signal output terminal is provided as thesignal output terminal 18 and a control code indicative of theprohibition of reproduction is detected from a watermark, the output ofthe output processing block 15 is not allowed to be output to theoutside of the apparatus through the signal output terminal 18 becausethere is a problem with reproduction control. However, when a controlcode indicative of the permission of reproduction is detected from awatermark, the output of the output processing block 15 is allowed to beoutput to the outside of the apparatus through the signal outputterminal 18.

When the digital signal output terminal is not provided as the signaloutput terminal 18, there is only an analog signal output, and it isconfirmed that an optical disk is normally produced, the output of theoutput processing block 15 is allowed to be output to the outside of theapparatus through the signal output terminal 18.

The watermark detection processing block 17 does not need to detectwatermarks directly from data 24 having a high data transfer rate bycarrying out watermark detection processing on data stored in the buffermemory and may detect watermarks from the data stored in the buffermemory 23, thereby eliminating a restriction on detection speed.Thereby, processing speed which enables practical watermark detection isensured while costs required for the addition of a watermark detectionfunction are reduced, which has been difficult to be solved in the priorart.

Generally speaking, the reproduction signal processing block 14 and thereproduction signal output processing block 15 are constructed in thesame device such as an LSI in an actual apparatus because data to beprocessed by these blocks have close relationship with each other andboth blocks need a data buffer memory for temporarily storing theprocessed data. The data buffer memories for temporary storing thesedata (not shown) share a single memory block frequently. For the samereason as above, the incorporation of the data buffer control block 16of the present invention in the above LSI and the use of the buffermemory 17 as the above buffer memories may be included in an embodimentof the present invention. Therefore, the block constitution shown inFIG. 1 is illustrated according to each functional block for theconvenience of explanation, and the embodiment of the present inventionand the actual LSI constitution are not limited to this.

The reason that the exclusive data bus 25 is used for the communicationof the above reproduction control data between the watermark detectionprocessing block 17 and the system control processing block 19 is givenbelow. The reason for the use of the exclusive data bus is that datatransferred over the data bus is information essential to reproductioncontrol and technical means which will be described hereinafter is madeeasy-to-use in order to prevent the invalidation of reproduction controlwhen the data is stopped or modified illegally.

A specific means of coping with stoppage is to confirm the connection ofa right party by exchange authentication data to authenticate that theparty has a fair right. A specific means of coping with modification isto use keys to encode data and transfer them over the bus so that thedata are prevented from being decoded and modified. The above technicalmeans for preventing illegal act on reproduction control information mayuse a method similar to a technique called “authentication” or “keyexchange” which has been carried out between a DVD-ROM drive and a DVDdecoder. The data is encoded using the authentication data andsubsequently decoded using the same authentication data.

Data processing for watermark detection in the present invention will beoutlined hereinafter. An aspect of the invention is that the data buffercontrol block 16 can provide sufficient buffering and buffer control sothat the data delivered to output control processor 15 occurs at a datarate that is different from the data being delivered the detectionprocessing block 17. In an embodiment of the invention, the detectionprocessing block issues a signal indicating the data rate at which thedata buffer control block is to deliver the data. A further aspect ofthe invention is that the detection processing block 17 can output dataat a rate different from the data rate at which it receives data.

A description is subsequently given of the method of controlling thebuffer memory 23 by means of the data buffer control block 16.

FIG. 2 is a flowchart of an example of the method of controlling thebuffer memory for watermark detection in the present invention.

After the system control processing block 19 starts the reproduction ofdata (step 1), initialization is first carried out (step 2) and thendata for starting writing to the buffer memory 243 is retrieved (step3). When the data of interest is found, writing to the buffer memory isstarted (step 4). When a predetermined amount of data required forwatermark detection is written to the buffer memory, writing to thebuffer memory is suspended (step 5). Thereafter, reading data forcarrying out watermark detection from the buffer memory is started (step6) and input into the watermark detection processing block 17 to startthe processing of watermark detection (step 7). When the processing ofwatermark detection by the watermark detection processing block ends(step 8), the data buffer control processing block 10 is informed of theend of detection processing. Since data stored in the buffer memory 23is not necessary until then, the buffer memory is initialized again(step 1). Afterward, the above operation is carried out during thereproduction of data as required.

FIG. 3 shows an example of data flow related to the watermark detectionoperation of a data reproduction apparatus having a watermark detectionfunction according to the present invention.

When the reproduction of data from an optical disk is started, data 24reproduced by the reproduction signal processing block 14 is input intothe data buffer control block 16. This data 24 is retrieved to findwhether the data includes data which needs watermark detection. When thedata includes data which needs watermark detection, the data buffercontrol block 16 stores a part which may include a watermark of theinput data in the buffer memory 23. At this point, the start positionand amount of the data to be stored should be specified by the formatused when watermarks are embedded. This watermark embedding format isgenerally hidden and the details of this format are not necessary in thepresent invention. Therefore, its description is omitted but the databuffer control block 16 operates to temporarily store data whose amountis larger than the minimum unit of data required for watermark detectionin the buffer memory 23.

When writing data ends, reading data is started and the read data isinput into the watermark detection processing block 17 to carry out theprocessing of watermark detection. When a signal indicative of the endof the processing of watermark detection is transmitted from thewatermark detection processing block 17 to the data buffer control block16, the data buffer control block 16 starts the retrieval of the data 24again to store data which may include a watermark in the buffer memory23.

The above embodiment will be described in more detail. FIG. 5 shows anexample of data flow related to the watermark detection operation of adata reproduction apparatus having a watermark detection functionaccording to the present invention of FIG. 3. The apparatus is based onthe assumption that signals input into the data buffer are a stream ofMPEG2 signals and a watermark is embedded in an I picture portion. It isassumed that the amount of data stored in the buffer memory 23 at onetime as the minimum unit for watermark detection is the amount of dataof two continuous I pictures.

In the above case, the data buffer control block 16 detects the head ofthe I picture and starts writing data to the buffer memory 23 fromthere. When the data of the two continuous I pictures are stored in thebuffer memory 23, writing data to the buffer memory 23 ends and then thewatermark detection processing block 17 starts reading data from thebuffer memory 23. The processing of watermark detection is started fromthe read data and when the processing of watermark detection ends, thedetection result is transferred to the system control processing block19 (not shown). Meanwhile, the data stored in the buffer memory 23becomes unnecessary after the end of watermark detection processing, thedata buffer control block 16 detects the head of the I picture again andstarts writing data to the buffer memory 23 from there.

The above processing is carried out repeatedly as required to carry outwatermark detection.

FIG. 4 shows another example of data flow related to the watermarkdetection operation of a data reproduction apparatus having a watermarkdetection function according to the present invention like FIG. 3.

Descriptions of the same portions as in FIG. 3 are omitted and differentportions will be described hereinafter.

The difference between the data flow of FIG. 3 and the data flow of FIG.4 is that the timing of starting writing data to the buffer memory 23 isafter the end of watermark detection in FIG. 3 whereas it is after theend of watermark detection in FIG. 4. Thereby, the timing of writingdata is relatively advanced and the timing of ending writing data isaccordingly advanced, whereby the cycle from the start of writing datato the start of writing next data is shortened.

That is, in the case of FIG. 3, T=data write time+watermark detectiontime.

On the other hand, in the case of FIG. 4,

T=data write time+data read detection time.

When watermark detection time>data read detection time, T can beshortened and the throughput of watermark detection can be improved.

As in FIG. 5, an example of the above embodiment will be described inmore detail hereinafter. FIG. 6 shows an example of data flow related tothe watermark detection operation of a data reproduction apparatushaving a watermark detection function according to the present inventionof FIG. 4. This apparatus is based on the assumption that signals inputinto the data buffer are a stream of MPEG2 signals and a watermark isembedded in an I picture portion. It is assumed that the amount of datastored in the buffer memory 23 at one time as the minimum unit forwatermark detection is the amount of data of two continuous I pictures.

In the above case, the data buffer control block 16 detects the head ofthe I picture and starts writing data to the buffer memory 23 fromthere. When the data of the two continuous I pictures are stored in thebuffer memory 23, the writing of data to the buffer memory 23 ends, andthe watermark detection processing block 17 starts reading data from thebuffer memory 23. The processing of watermark detection is started fromthe read data and when the processing of watermark detection ends, thedetection result is transferred to the system control processing block19 (not shown). Meanwhile, the data stored in the buffer memory 23becomes unnecessary after the data is read the data buffer control block16 detects the head of the I picture again and starts writing data tothe buffer memory 23 from there. The above processing is carried outrepeatedly as required to detect watermarks.

A useful function added to the data buffer control processing block 16will be described hereinafter. Generally speaking, an optical disk driveis generally used for various types of media so that different types offormatted data are transmitted to a reproduction data bus in the driveaccording to optical disk media to be reproduced. Therefore, a dataformat conversion function is provided to the data buffer control block16. Thereby, the watermark detection processing block 17 may handle aspecified data format. As a matter of course, a circuit block having adata format conversion function is not limited to the data buffercontrol block 16 and may be the watermark detection processing block 17.The same data sequence is not written to the buffer memory or read fromthe buffer memory but only a required data portion is rearranged basedon a predetermined format and read so that data to be written to thebuffer memory and data to be read from the buffer memory are rearrangedto convert the format of the data.

Consequently, it is possible to provide the object of adjusting the datatransfer rate to eliminate the difference between the high data transferrate of the data 24 and the data transfer rate which enables theprocessing of the watermark detection processing block 17 and the objectof converting the data format of the data 24 into a data format whichcan be accepted by the watermark detection processing circuit block 17to the data buffer control block 16 and the buffer memory 23.

In the description of the above embodiment, data to be stored in thebuffer memory 23 out of the data 24 is continuous data starting from aspecific portion which may include a watermark. The present invention isnot limited to this and the data may be a specific extract which mayinclude a watermark. Thereby, the capacity of the buffer memory can bereduced.

A required portion of data for watermark detection may be retrieved andused when data which starts from an arbitrary position is stored andread. Thereby, data buffer control can be simplified.

In the explanation of the above embodiment, there has been described amemory control method in which the data buffer control block 16 does notread data from the buffer memory 23 while it writes data to the buffermemory 23 and starts reading data after the end of writing. The presentinvention is not limited to this and a memory control method in whichwriting and reading are carried out alternately on a time-division basismay be employed. Since data reading and watermark detection processingcan be thereby started almost at the same time, the throughput ofwatermark detection can be improved. The throughput can be also improvedby using a memory having a plurality of data ports as the buffer memory23 to write and read at the same time.

According to the present invention, since the first data on whichwatermark detection is made is stored in the data storage means having abuffer memory function and watermark detection can be made on the datastored in the data storage means, watermark detection does not need tobe made from the first data having a high data transfer rate directly,thereby eliminating a restriction on detection speed. Since data storedin the data storage means is updated again after one time of watermarkdetection ends and watermark detection is made on the updated firstdata, embedded watermarks can be detected intermittently. Therefore,even when a watermark cannot be detected correctly at the time of onetime of detection due to signal deterioration or the like, thesubsequent detection result is used to carry out the processing ofreproduction control. Therefore, the problem of costs required for theaddition of a watermark detection function and the problem of processingspeed which enables watermark detection can be solved at the same time.

1. An apparatus for playing back data stored on an information recordingmedium, the data having audio information, visual information, oraudio-visual information, the data containing a watermark, the apparatuscomprising: a reproduction processing circuit configured to receive theinformation that is stored on the information recording medium toproduce the data; and playback circuitry comprising: a data store; adata selection circuit configured to select a subset of the data whichis necessary for the detection of the watermark and to store the subsetof the data into the data store; a detecting circuit coupled to the datastore and configured to process data contained therein to produce adetection result, the detection result being based on the watermark; anda control circuit configured to selectively output the data based on thedetection result, wherein the data selection circuit and the detectingcircuit operate in alternating fashion to alternate between storing asubset of the data to the data store and reading out the subset of thedata for watermark detection.
 2. The apparatus of claim 1 furthercomprising a data selection circuit configured to select a first subsetof the data, the data selection circuit coupled to deliver the firstsubset to the data store, wherein the detecting circuit processes thefirst subset.
 3. The apparatus of claim 2 wherein the capacity of thedata store is equal to or greater than the minimum size of the firstsubset.
 4. The apparatus of claim 2 wherein the detecting circuit isfurther configured to produce a signal indicating the completion ofprocessing of the first subset, wherein the selection circuit selects,in response to the signal, a second subset of the data, and wherein thesecond subset replaces the first subset.
 5. The apparatus of claim 2wherein the detecting circuit is further configured to indicate that thefirst subset has been delivered to the data store, and wherein theselection circuit selects, in response thereto, a second subset from thedata for delivery to the data store.
 6. The apparatus of claim 2 whereinthe data is an ISO-MPEG 2 formatted data stream, and wherein the firstsubset is an I-picture.
 7. The apparatus of claim 1 further including adata bus coupled only between the detection circuit and the controlcircuit, wherein the detection circuit produces a signal representativeof the detection result, the signal being sent to the control circuitvia the data bus.
 8. The apparatus of claim 1 wherein the detectioncircuit produces a signal representative of the detection result, thedetection circuit further configured to encode the signal using adecryption key, the control circuit further configured to receive theencoded signal and to decode the signal using the decryption key.
 9. Theapparatus of claim 1 wherein the detection circuit produces a signalrepresentative of the detection result, wherein the detection circuitand the control circuit are further configured to exchangeauthentication data with each other, and wherein the detection circuitis further configured to deliver the signal to the control circuit whenthe detection circuit makes a positive determination that the controlcircuit is permitted to receive the signal.
 10. The apparatus of claim 9wherein the detection circuit is further configured to encode the signalusing the authentication data, and the control circuit is furtherconfigured to receive the encoded signal and to decode the signal usingthe authentication data.
 11. The apparatus of claim 1 wherein thedetection circuit produces a first signal when processing of data in thedata store produces the detection result a first predetermined number oftimes in succession, the control circuit selectively outputting thefirst data in response to the signal.
 12. The apparatus of claim 11wherein the detection circuit, subsequent to producing the first signal,produces a second signal when processing of data in the data storeproduces a second detection result a second predetermined number oftimes in succession, the control circuit selectively outputting thefirst data in response to the first and second signals.
 13. Theapparatus of claim 1 wherein the first data is ISO-MPEG 2 formatted. 14.The apparatus of claim 1 wherein the data store receives at least someof the data at a data rate equal to a data rate at which thereproduction processing circuit produces the data.
 15. The apparatus ofclaim 1 wherein the data store receives a subset of the data at a firstdata rate equal to a data rate at which the reproduction processingcircuit produces the data, wherein the detecting circuit is furtherconfigured to indicate a second data rate and the data store is furtherconfigured to output the data contained therein at the second data ratein response thereto.
 16. The apparatus of claim 1 wherein the detectingcircuit is further configured to receive data contained in the datastore at a third data rate and process the data to produce a detectionresult at a fourth data rate, wherein the fourth data rate is equal toor greater than the third data rate.
 17. An apparatus for playing backdata stored on an information recording medium, the data containing awatermark, the apparatus comprising: a reproduction processing circuitconfigured to receive the information that is stored on the informationrecording medium to produce the data; and playback circuitry comprising:a data store; a data selection circuit configured to select a subset ofthe data which is necessary for the detection of the watermark and tostore the subset of the data into the data store; a detecting circuitcoupled to the data store and configured to process data containedtherein to produce a detection result, the detection result being basedon the watermark; and a control circuit configured to selectively outputthe first data based on the detection result and the type of theinformation recording medium, wherein the data selection circuit and thedetecting circuit operate in alternating fashion to alternate betweenstoring a subset of the data to the data store and reading out thesubset of the data for watermark detection.
 18. A method in a playbackdevice for playing back data, the data having audio information, visualinformation, or audio-visual information, the data containing awatermark, the method comprising: receiving the data from theinformation recording medium; selecting a subset of the data which isnecessary for the detection of the watermark; storing the subset of thedata in a data store; the playback component producing a detectionresult by processing data in the data store, the detection result basedon the watermark; the playback component selectively outputting the databased on the detection result; and reading out the subset of the data,wherein the storing the subset of the data and the reading out thesubset of the data operates in alternating fashion for watermarkdetection.
 19. The method of claim 18 wherein selectively outputting isfurther based on the type of the data source.
 20. An apparatus forplaying back data having audio information, visual information, oraudio-visual information, the data containing a watermark, the apparatuscomprising: first means for providing the data from an informationrecording medium; and a playback component comprising: second means,coupled to the first means, for storing a subset of the first data whichis necessary for the detection of the watermark into a data store; thirdmeans for producing a detection result, including means for processingdata stored in the second means, the detection result being based on thewatermark; and fourth means, operatively coupled to the third means, forselectively outputting the data based on the detection result, whereinthe second means and the third means operate in alternating fashion toalternate between storing a subset of the data to the data store andreading out the subset of the data for watermark detection.
 21. Anapparatus for playing back data having audio information, visualinformation, or audio-visual information, the data containing awatermark and stored in an information storage medium, the apparatuscomprising: a reproduction processing circuit configured to receiveinformation stored on the information recording medium; and playbackcircuitry to reproduce the data containing the watermark, the playbackcircuitry comprising: a detecting circuit configured to detect thewatermark; a data selection circuit configured to select a subset of thedata which is necessary for the detection of the watermark; a data storeconfigured to store the subset; and a reproduction control circuitconfigured to control the reproduction of the data depending upon aresult of the detection of the watermark by the detecting circuit,wherein the data store is shared by the reproduction processing circuitand the detecting circuit, wherein the data selection circuit and thedetecting circuit operate in alternating fashion to alternate betweenstoring a subset of the data to the data store and reading out thesubset of the data for watermark detection.
 22. The apparatus of claim1, wherein the watermark represents copyright protection information onthe data.
 23. The apparatus of claim 17, wherein the watermarkrepresents copyright protection information on the data.
 24. Theapparatus of claim 20, wherein the watermark represents copyrightprotection information on the data.